<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <canvas id="canvas" width="600" height="400"></canvas>
  <script>
    var canvas=document.querySelector("#canvas")
    var hb=canvas.getContext("2d")
    var yuan=new Path2D()
    yuan.arc(200,200,100,0,Math.PI*2)
    hb.fillStyle="red"
    hb.fill(yuan)
    hb.fillStyle="blue"
    hb.arc(100,100,100,0,Math.PI*2)
    hb.fill()
    hb.fillStyle="yellow"
    hb.arc(300,100,100,0,Math.PI*2)
    hb.fill()
  </script>
</body>
</html>